Running in reverse? you mean you can get the motor to spin in the opposite direction by swapping ignition wires??
if so a dpdt relay, a switch, a cut helix and presto reverse??
What about timming? maybe an aftermarket brain?
a guy i ride with added rev kit to his 600 pro x. Came with a double cut helix, a brain to handle the timming changes (oem) and a button to mount on the bar wired to the brain... that was it, took no time to install.
COULD IT BE DONE TO A V4?